* New primop builtins.filterSource, which can be used to filter files

from a source directory.  All files for which a predicate function
  returns true are copied to the store.  Typical example is to leave
  out the .svn directory:

    stdenv.mkDerivation {
      ...
      src = builtins.filterSource
        (path: baseNameOf (toString path) != ".svn")
        ./source-dir;
      # as opposed to
      #   src = ./source-dir;
    }

  This is important because the .svn directory influences the hash in
  a rather unpredictable and variable way.

src/libutil/archive.hh

@@ -45,16 +45,16 @@ namespace nix {
 
      `+' denotes string concatenation. */
 
-struct DumpFilter
+struct PathFilter
 {
-    virtual ~DumpFilter() { }
+    virtual ~PathFilter() { }
     virtual bool operator () (const Path & path) { return true; }
 };
 
-extern DumpFilter defaultDumpFilter;
+extern PathFilter defaultPathFilter;
 
 void dumpPath(const Path & path, Sink & sink,
-    DumpFilter & filter = defaultDumpFilter);
+    PathFilter & filter = defaultPathFilter);
 
 void restorePath(const Path & path, Source & source);